This invention relates generally to micromechanical elements such as movable joints, gears, and sliders and, more particularly, concerns fabrication methods for making high precision micromechanical elements with floating bushings.
Micromechanical elements with joints that slide or rotate have many uses in miniature pin joints, gears, cranks, slides, and other mechanisms. These elements can be made in a variety of ways. In U.S. Pat. No. 4,740,410 by Muller et al., micromechanical sliding or rotating elements are made by following the process steps of:
1) depositing a sacrificial layer of glass on a substrate, PA1 2) depositing and forming a structural layer of polysilicon for the sliders or gears, PA1 3) depositing a second sacrificial layer of glass, PA1 4) depositing and forming a second structural layer of polysilicon for the rails or pins, PA1 5) removing the sacrificial layers to free the gears and sliders from both the substrate and the pins and rails.
This process results in fixed axle pin joints or fixed rail sliders. Once loosened, the fixed gears and sliders rest on the substrate. In operation, undesirable amounts of friction are generated between the gears or sliders and the substrate.